Characterization of Hydroxypropyl Tapioca Starch and its Pregelatinized Starch as Tablet Disintegrants

Abstract

Hydroxypropyl tapioca starches (HPTS) and pregelatinized hydroxypropyl tapioca starches (PG-HPTS) with different molar substitutions are characterized as tablet disintegrants in comparison with native tapioca starch (NTS). Powder XRD and polarized light microscopy indicates that HPTS is A-type crystalline starch similar to NTS, whereas PG-HPTS is amorphous. Compared to HPTS, an increase in swelling capacity with higher degree of hydroxypropyl substitution is observed with PG-HPTS. All tablets containing NTS, HPTS, and their pregelatinized starches at 5% and 10% show fast disintegration within 8 min. Interestingly, the tablets with disintegration times of less than 30 s are obtained when NTS and HPTS are used. The tablets containing PG-HPTS with higher degree of hydroxypropyl substitution show longer disintegration time and more retarded drug dissolution when compared to those with non-pregelatinized starches. This might be attributed to higher water sorption and subsequent swollen gel formation of PG-HPTS. The effect of hydroxypropylation on tablet disintegration and dissolution is clearly observed with PG-HPTS. The results revealed that the functionality of PG-HPTS is dependent on the degree of hydroxypropyl substitution, but less dependence is observed with HPTS. In conclusion, HPTS and PG-HPTS with different molar substitutions could be used as disintegrants in tablet formulation.